Added API to handle successful search in some panel in options window.
By default no action is performed. Each implementor should make special actions,
for example to choose a specific sub-panel, if this is required.

Include/exclude patterns may contain either a regular expression defining
files relatively to userdir (see MyItem1) or a compound pattern defining
files and property keys (see MyItem2). A compound pattern consists of
file regex pattern followed by hash delimiter (#) then property key
regex pattern followed by another hash delimiter. Hash delimiter can be
ommited at the end of compound pattern. For example, a compound pattern
can have the following structure
filePattern1#keyPattern1#|filePattern2|filePattern3#keyPattern3.